RT Journal Article
SR Electronic
T1 Kinetochore stretching inactivates the spindle assembly checkpoint
JF The Journal of Cell Biology
JO J Cell Biol
FD Rockefeller University Press
SP 383
OP 390
DO 10.1083/jcb.200811028
VO 184
IS 3
A1 Uchida, Kazuhiko S.K.
A1 Takagaki, Kentaro
A1 Kumada, Kazuki
A1 Hirayama, Youko
A1 Noda, Tetsuo
A1 Hirota, Toru
YR 2009
UL http://jcb.rupress.org/content/184/3/383.abstract
AB The spindle assembly checkpoint (SAC) monitors the attachment of microtubules to the kinetochore and inhibits anaphase when microtubule binding is incomplete. The SAC might also respond to tension; however, how cells can sense tension and whether its detection is important to satisfy the SAC remain controversial. We generated a HeLa cell line in which two components of the kinetochore, centromere protein A and Mis12, are labeled with green and red fluorophores, respectively. Live cell imaging of these cells reveals repetitive cycles of kinetochore extension and recoiling after biorientation. Under conditions in which kinetochore stretching is suppressed, cells fail to silence the SAC and enter anaphase after a delay, regardless of centromere stretching. Monitoring cyclin B levels as a readout for anaphase-promoting complex/cyclosome activity, we find that suppression of kinetochore stretching delays and decelerates cyclin B degradation. These observations suggest that the SAC monitors stretching of kinetochores rather than centromeres and that kinetochore stretching promotes silencing of the SAC signal.